The IFS system is currently being worked on and I have most of the UI finished. You can preview the system here: https://www.airlineenterprise.com/airline/ifs (The game may log you out - not sure why that happens. Just log back in and click the link again). Click the yellow "view costs & info" button to read about how the IFS system will work once it is implemented. The cost structures are mostly final but still subject to change prior to release.

Shorter flights do not require a maxed-out IFS system. I am working on a formula that dictates a required rating to maintain 100% reputation at different flight time intervals. Passengers on a 2 hour flight will not expect the same level of service as an 8 hour flight for example. This will require you to create several service configurations for the different types of routes that you operate.

Changes to the reputation system:
Shortly after IFS is implemented, the reputation system will be completely changed. Each of your flights will be assigned an overall reputation. 50% of this will come from the IFE/Cabin Config assigned to that flight, and 50% will come from the IFS config assigned to that flight. You will no longer accumulate reputation points for each flight you complete. Instead your airline reputation will be calculated from the average reputation of all your flights. Reputation will be calculated once per week and will consist of the average flight reputation for all your flights flown that week.

This will allow players to differentiate their airline from other airlines by choosing what type of airline they want to run. A low-cost carrier would have a lower reputation due to a less appealing IFE/IFS configuration, but would also be less costly to operate. Likewise a full-service carrier would have a better reputation but also higher costs of operation. There will not be a "right" or "wrong" way of running your airline - both methods would work, it's just a matter of how you want to manage your airline.

I see a problem here: If demand depends on reputation, and reputation only updates once a week, then how are you meant to function in the first week of operations? When you start out you haven't flown any flights yet, so what would reputation be based on, and how would demand be calculated?

At the moment that's not supported but it may come at some point in the future. Cause it's not as simple as just allowing you to set individual prices, those prices also have to have some sort of affect which means more alterations to the demand formula and other things. I want to get this pushed out before December, get the reset and server move out of the way and then we can go back and re-evaluate features and such.

The charge you enter is considered to be the total cost for that category.

Let airlines raise their reputation by paying. "Will that 50M go to the acquisition of an aircraft or to a TV ad that will raise your reputation by 4% every week? +1% and cost 5M more if it's a popular celebrity" That kind of thing. Consumers are gullible.